This invention relates to a hydraulic system for an agricultural implement, e.g. a disk harrow and more particularly to such a system which will automatically control the elevation of the farm implement.
The operation of an agricultural implement, in a specific embodiment a large trail behind type, in the field requires the constant attention of the operator of the host tractor pulling the implement. The direction and speed of the tractor must be controlled carefully for maximum efficiency. For instance, when the tractor operator is tilling a field using a disk harrow the elevation and penetration of the cultivator disks has to be set within an operative range to give adequate tillage performance and to minimize the draft load on the host tractor. Oftentimes as the implement is dragged across the field varying soil conditions are encountered requiring adjustment of the cultivator disks to assure optimum performance. Adjustment, for instance, of the elevation of a disk harrow is best accomplished from inside the operator's cab on the tractor vehicle. Furthermore, when the tractor and its attendant implement get to the headland of the field the reversing of the direction of the tractor places a large burden on the operator, as the operator must turn the vehicle while raising and lowering the trail behind implement. This operation must be performed quickly and with a high degree of precision. After the tractor vehicle and the implement have been turned around and are heading back down the field the operator must now set the optimum working height of the trail behind implement. This is most easily accomplished from inside the cab as it would prevent the need for the operator to stop the tractor, dismount from the tractor and adjust the implement.
It is known in the prior art to provide automatic depth control for a trail behind implement. It is also taught in U.S. patent application Ser. No. 156,896, now U.S. Pat. No. 4,337,959, entitled "Self Leveling and Height Control Hydraulic System", assigned to the same assignee as this invention, to utilize a rotary flow divider in maintaining disk harrow position control. The contribution that the instant invention makes to the prior art is that a trail behind implement, in this case a disk harrow, utilizes a rotary flow divider for self-leveling and height control and also incorporates an electrical sensing circuit for sensing the position of the implement and communicating this information to the tractor vehicle operator in the operator's work station. Furthermore, the operator's work station incorporates a manual control element for adjusting the height of the trail behind implement relative to the ground plane.
It is, therefore, an object of this invention to provide an electrical control system for cooperation with a hydraulic system of an implement which will be self-leveling and will provide automatic height control.
It is another object to provide a hydraulic system which is capable of performing certain operations on the trail behind implement automatically without the attention of, or only minimum attention of, the vehicle operator in the control of the implement.
Another object of the invention is to use a rotary flow divider to meter fluid flow to each of a plurality of hydraulic cylinders used in coordinating the elevation of a trail behind working implement. Another object of the invention is to provide an interface between the rotary flow divider and the operator's work station to enable the operator to control the height and self-leveling feature of the trail behind implement controlled by the rotary flow divider.